Spreadsheet tool for computing levee pond excavation costs for developing countries

The levee pond is by far the most popular pond type for fish production. The specific object of this study was to develop a tool enabling extension, nongovernmental organization (NGO) agents, contractors and engineers in developing countries for computing levee pond excavation costs. We developed a spreadsheet-based computational tool in English and Spanish on the Microsoft Excel^® platform. Knowing the original land slope and desired pond volume, one may compute excavation amounts that provide an acceptable cut-fill estimates based on a comparison with AutoCAD Civil 3-d^®. The model computes projected costs in user-selected currency. Guidelines are provided for establishing pond bottom elevations and achieving the desired water depth. The model is relevant for small to medium sized levee ponds customarily used in aquacultural production in developing countries.     

Shrimp Yields and Economic Potential of Intensive Round Pond Systems

Three intensive growout trials using Penaeus vunnumei were conducted in round ponds in Hawaii in 1987. A 337 m² experimental pond was stocked at 100 shrimp/m² for two trials; a 2,000 m² commercial prototype pond was stocked at 75/m² for one trial. In the experimental pond trials, shrimp survival averaged 88 ± 10% (SE) and feed conversion averaged 2.2 ± 0.2. Growth averaged 1.5 ± 0.3 g/week, yielding 18.2 ± 1.7 gram shrimp in 80 ± 5.5 days. Combined production in the experimental trials was 32,272 kg/ha in 174 days (from stocking of trial 1 to harvest of trial 2). Comparing these results to 1986 results (Wyban and Sweeney 1988), it was concluded that shrimp growth is not affected and production is doubled by increasing stocking density from 45/m² to 100/m². Pooling data from 1986 and 1987, a significant linear regression was obtained when weekly growth of shrimp above four grams individual size was regressed on mean weekly pond temperature: growth = 0.37 * temperature - 8.44, (r²= 0.41; P < 0.01). Multiple regression to examine effects of shrimp size, pond biomass, and shrimp age on the temperature-growth relationship was not significant. In the commercial prototype pond trial, survival was 67% and feed conversion was 2.0. Growth averaged 1.4 g/week, yielding 18.1 gram shrimp in 88 days. Production was 9,120 kg/ha. Individual shrimp size distribution at harvest in the commercial pond was similar to experimental pond results, indicating that shrimp growth in the two systems was comparable. Financial characteristics of a hypothetical 24 pond shrimp farm using these results were determined using an electronic spreadsheet model (hung and Rowland 1987). Feed costs were 40% of total operating costs while postlarvae and labor were 14% and 16% of total operating costs, respectively. Breakeven price (BEP) was far more sensitive to changes in revenuedetermining inputs such as survival and growth than to comparable changes in costdetermining inputs such as feed and postlarvae costs. Together these results suggest that commercial scale round pond production mimics experimental scale production and that round pond technology has commercial potential.     

The Impact of Aquaculture Pond Engineering Design on the Returns to Shrimp Farms

The effects of pond design on the internal rate of return of a 40 ha shrimp farm is evaluated. The influence of four pond construction parameters (pond size, pond shape, levee crown size and canal bank slope) on the total amount of earth moved and construction costs is determined using an engineering design model. The bioeconomic model, MARSIM, calculates returns to farms with the design modifications. Of the four parameters, the pond shape is the most influential over the range considered (from 17% to 8%). Pond size is the second most important parameter (from 17% to 21%). Levee width and canal bank slope influence are of lesser importance (<1% change).     

Agglomeration externalities and technical efficiency: An empirical application to the pond aquaculture of Pangas and Tilapia in Bangladesh

This article analyzes the effects of agglomeration externalities on productivity and efficiency by applying a stochastic production frontier model with a technical inefficiency model to the aquaculture industry. Agglomeration externalities refer to the costs and benefits to firms from clustering. Agglomeration studies within aquaculture have focused on the intensive salmon industry, whereas this study focuses on low-technology, extensive pond aquaculture, representing most farmers in the developing world and using Bangladesh as an empirical case. The results show that there is a positive externality effect of regional industry size on the production possibility frontier and a negative effect on technical efficiency. Farm density enhances efficiency and the farm proximity to output markets decreases efficiency. Thus, policies aimed at increasing aquaculture pond production in developing countries should consider farm locations and their access to input and output markets, all of which affect farm productivity and efficiency.     

Effect of high phosphate fertilization rate on pond phosphate concentrations,chlorophyll <Emphasis Type="Italic">a</Emphasis>, and fish growth in carp polyculture

The effect of different application rates of triple superphosphate (22.4, 44.8, and 67.2 kg P₂O₅ ha⁻¹) was observed on total and available phosphorus concentrations in pond soil, total and filterable orthophosphate concentrations in pond water, chlorophyll a, and fish growth in a carp polyculture system during summer (22–32°C) months to determine the economical dose of P₂O₅. pH, hardness, calcium and alkalinity of soil and water did not differ significantly among treatments (P > 0.05) and were within the desired ranges. Average total phosphorus concentrations in pond soil were not significantly different between treatments but available phosphorus (P > 0.05) in pond soil, total phosphorus (P > 0.001), and filterable orthophosphate (P > 0.0001) concentrations in pond water, chlorophyll a (P > 0.0001), and net fish production (P > 0.01) were significantly higher in fertilized ponds than in controls. Overall, fish yield did not significantly differ among treatments, suggesting that a very high dose of P₂O₅ may not be necessary for high yields. Reducing the dose of P₂O₅ could reduce cost without reducing fish production.     

Management of stocking density,pond size,starting time of aeration,and duration of cultivation for intensive commercial production of shrimp Litopenaeus vannamei

A dynamic stock model was used for quantification of shrimp production and analysis of alternative management schemes of stocking density, pond size, starting time of aeration, and duration of cultivation for intensive commercial production of the shrimp Litopenaeus vannamei. Databases from Mexican farms were used to calibrate the model. Multiple linear regression models were employed to establish relationships between parameters of the stock model and the management variables. Water quality variables (dissolved oxygen, temperature, and salinity) were complementarily analyzed. The final weight of shrimp was directly related to duration of cultivation and dissolved oxygen, and inversely related to stocking density, pond size, and salinity. There were inverse relationships between the growth coefficient and temperature and dissolved oxygen and between mortality rate and temperature. Dissolved oxygen was significantly related to starting time of aeration. Simple linear regression and an equivalence test indicated that biomass at harvest (after 13 weeks in winter, and 20 weeks in summer) was adequately predicted by using the stock model and the multiple regression models. The highest production (winter, 6900 kg ha⁻¹; summer, 12,600 kg ha⁻¹) were predicted using 60 postlarvae m⁻², small ponds (2 ha), and starting aeration at the first week of cultivation; while the lowest yields (winter, 2600 kg ha⁻¹; summer, 6000 kg ha⁻¹) were obtained using 40 postlarvae m⁻², large ponds (8 ha), and delaying the start of aeration until the fifth week of cultivation. The lowest production was 38% (winter) and 48% (summer) of the highest yield. Using small ponds could be particularly important during winter cycles to increase production, while stocking density and starting time of aeration contributed less. In contrast, pond size played a minor role during summer cycles and stocking density was the most sensitive variable.     

Determination of critical limits of soil nutrients for use in optimizing fertilizer rates for fish ponds in red, lateritic soil zones

Mesocosms containing lateritic soil from West Bengal, India and de-ionized water were treated with different amounts of nitrogen (N), phosphorus (P), and potassium (K) fertilizers. Concentrations of available N, P, and K in soils and gross primary productivity were measured for the mesocosms. Critical concentrations of the three nutrients were estimated by the graphical method of Cate and Nelson that has been used widely for establishing critical soil nutrient concentrations in fertilization research on terrestrial crop plants. Critical concentrations of the three nutrients were: available N, 200 mg kg⁻¹; available P, 13 mg kg⁻¹; available K, 80 mg kg⁻¹. Ponds sited in red, lateritic soil in West Bengal were treated monthly with 20, 15, and 3 kg ha⁻¹ application⁻¹ of N, P, and K, respectively. There was an increase in gross primary productivity when the critical concentrations of available N, P, and K established in the mesocosm study were attained in the pond soils. Fish production in fertilized ponds is positively correlated with gross primary productivity. Thus, the concept of critical nutrient concentrations in soils could be a valuable tool in pond fertilization research.     

Selection of aerators for intensive aquacultural pond

Aeration cost is the third largest cost in intensive aquaculture system after post larvae and feed cost representing about 15% of total production cost. Therefore, selection of aerators plays a major role in maximizing the profit in such system. Over the years, various types of aerators have been developed specifically to enhance the production of aquatic species. The performances of these aerators are generally compared in terms of standard aeration efficiency. However, suitability of a particular aerator at different pond sizes and water quality conditions can best be determined in terms of aeration cost per unit time of operation. In the present study, economic performance of five different aeration systems – circular stepped cascade (CSC), pooled circular stepped cascade (PCSC), 1-hp paddle wheel, 2-hp paddle wheel and propeller aspirator pump were evaluated and compared at different pond sizes, initial DO concentrations of pond and operating hours of aerators; assuming a typical Indian major carp (IMC) culture with commonly practiced stocking density and feeding. Both CSC and PCSC aerators were found to be suitable for pond size less than 1000 m³. However, for pond sizes more than 5000 m³, 1-hp paddle wheel and 2-hp paddle wheel aerators were found to be efficient.     

Operating costs and health management strategies in shrimp hatcheries

Abstract

This paper presents a study of operating costs in shrimp hatcheries. Size effects are presented for fixed, variable, unitary, and marginal costs. Cost structures by functional production department and by cost‐category are discussed for a hypothetical 100‐million postlarvae/month hatchery in an industrialized country, and compared to those of a hatchery in a developing country. Health management issues, mainly measures commonly used to manage bacterial diseases, and their economic impact are discussed, focusing on the trade off between survival rates and sanitation down‐time.

Salaries and benefits represent the largest cost‐component (37%) for hatcheries in industrialized countries, while feeds and operating supplies constitute the most important costs in developing countries (60%). The need to import hatchery feeds and other operating supplies into developing countries works against savings from lower labor costs typical of developing countries.

Total fixed costs depend on the size of a hatchery and are constant for all possible levels of output. Average fixed cost per unit (thousand postlarvae) can be reduced by producing high postlarval outputs. Hatcheries in areas with seasonal shrimp crops face the challenge of covering fixed costs with revenue from a short production season. Hatcheries with large fixed costs can operate in a cost‐efficient manner only by producing high levels of output. Average total cost and average variable cost curves follow a U‐shaped curve, in which costs first decline as output increases, then reach a minimum, and finally increase as output increases above a point of diminishing returns.

In hatcheries total costs are independent of larval survival, but lower output resulting from low survival increases unit costs. This effect is more pronounced at lower levels of output. Bacterial diseases decrease survival rates and increase unit costs.     

Comparative costs of postlarval production from wild or domesticated Kuruma shrimp, Penaeus japonicus (Bate), broodstock

The present study compares the relative costs of stocking ponds with postlarvae from wild or domesticated Kuruma shrimp, Penaeus japonicus (Bate), broodstock. Wild broodstock were obtained from a commercial trawler. Domesticated broodstock were reared to harvest size (wet weight = 25 g) on a commercial farm and then transferred to controlled environment tanks where they were grown to a final wet weight of 50 g. The costs of stocking ponds with postlarvae were calculated from the observed reproductive output, the costs of purchasing wild broodstock and the costs of domesticated broodstock production in the controlled environment facility. Domesticated P. japonicus spawned comparable numbers of eggs to wild broodstock of similar size, but hatching success was significantly lower. A total of 12 domesticated P. japonicus broodstock would be needed to produce the postlarvae to stock a 1-ha pond, compared to only six wild broodstock. However, the much higher relative costs of wild broodstock means that the cost of using their postlarvae would be Aus$851 per pond compared to Aus$390 for domesticated broodstock. The present authors conclude that the use of domesticated P. japonicus broodstock could be a cost-effective alternative to wild broodstock in Australia and in other countries where P. japonicus is farmed.     

Evaluation of Nile tilapia pond management strategies in Egypt

Five pond management strategies for Nile tilapia Oreochromis niloticus L. production were evaluated in 0.1‐ha earthen ponds in Egypt during a 145‐day production cycle. Pond management strategies developed by the Pond Dynamics/Aquaculture Collaborative Research Support Programme (PD/A CRSP) were compared with a traditional and a modified Egyptian pond management strategy. Young‐of‐year Nile (mixed‐sex or sex‐reversed) tilapia were stocked into ponds at 20 000 fish ha^?1. Sex‐reversed tilapia were stocked into chemical fertilization, organic fertilization plus formulated feed and feed only treatment ponds, whereas mixed‐sex tilapia were stocked into organic fertilization plus formulated feed and chemical plus organic fertilization plus formulated feed treatment ponds. Nile tilapia yields ranged from 1274 to 2929 kg ha^?1. Nile tilapia yields in organic fertilization plus formulated feed treatments were significantly greater than the yield from chemical fertilization ponds. PD/A CRSP pond management strategies did not produce significantly greater Nile tilapia yields than the traditional Egyptian system, but a larger percentage of harvested tilapia in the organic fertilization plus feed treatments were classified in the first and second class size categories compared with the traditional Egyptian system. Organic fertilization plus formulated feed pond management strategies had the highest net returns, average rate of return on capital and the highest margin between average price and break‐even prices to cover total variable costs or total costs.     

A stochastic approach for analysis of the influence of white spot disease, zootechnical parameters, water quality, and management factors on the variability of production of shrimp Litopenaeus vannamei cultivated under intensive commercial conditions

We investigated the variability of shrimp Litopenaeus vannamei production by incorporating stochastic elements into deterministic stock models and determined the contribution that white spot disease, zootechnical parameters, water quality, and alternative management strategies have on variability. The model was calibrated for intensive shrimp cultivation in the State of Nayarit, Mexico. Mean annual production increased as a consequence of improved management from 8000 kg ha⁻¹ to 22,000 kg ha⁻¹ when cultivation was not affected by the disease and from 3200 kg ha⁻¹ to 10,400 kg ha⁻¹ when the disease affected production. When simultaneously considering both cases, mean annual production increased from 6300 kg ha⁻¹ to 16,800 kg ha⁻¹. White spot disease was a major factor determining variability of production. Shrimp production was particularly sensitive to levels of dissolved oxygen when management was inadequate, while final weight and mortality rate of shrimp were more sensitive when management improved. Water temperature and salinity had intermediate importance, and mortality caused by the disease and the time when mortality occurred had intermediate or low relevance. Improving management increased shrimp production and diminished variability. The duration of cultivation and stocking density were the most important management variables controlling variability of production when cultivation was affected by the white spot disease. When the disease was not present, pond size and duration of cultivation were the main factors affecting production. Starting time of aeration had relatively lower importance in determining variability, while the stochastic values of dissolved oxygen, in contrast, became most important. These results call for studies on improving aeration management to reduce variability of dissolved oxygen in ponds.     

Economics of milkfish (Chanos chanos) production in Hawaii*

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.     

Predicting night time dissolved oxygen loss in prawn ponds of Hawaii: Part II. A new method

Dissolved oxygen concentration (DO), water temperature and wind speed were monitored overnight at prawn (Macrobrachium rosenbergii) ponds of Amorient Aquafarm Inc. (Kahuku, Oahu) and at Brigham Young University-Hawaii (Laie, Oahu) from June to November 1985. A new model, the whole pond respiration-diffusion (WPRD) model, was developed to predict pond DO at dawn. The two components comprising the model were whole pond respiration and diffusion. Model inputs included a measurement of pond DO and water temperature at dusk, another DO and temperature measurement made several hours after the dusk measurement, and an estimate of the average wind speed for the night. For a lag of 3 h between the dusk and second DO measurement, the mean absolute deviation of the predicted dawn DO from the observed dawn DO was 0·40 mg O₂ liter⁻¹ (standard error of mean = 0·8 mg O₂ liter⁻¹), based on 40 verification trials. The WPRD model performed equally well for both calm nights (wind speed < 0·3 m s⁻¹) and for relatively windy nights (wind speed > 7 m s⁻¹).     

Production of astaxanthin from Haematococcus in open pond by two-stage growth one-step process

We have developed a two-stage growth one-step process for cultivation of Haematococcus using a self-designed system that mimics an open pond in the natural environment. The characteristics of this process are green vegetative cell growth and cysts transformation and pigment accumulation that proceed spontaneously and successively in one open photobioreactor. Four strains of Haematococcus (H. pluvialis 26; H. pluvialis 30; H. pluvialis 34; H. pluvialis WZ) were cultured in this imitation system for a duration of 12 days. The changes in cell density and medium pH were closely monitored, and the astaxanthin content and yield of the four Haematococcus strains were measured at the end of 12 days of cultivation. Two of the strains, H. pluvialis 26 and H. pluvialis WZ, were selected as strains suitable for mass culture, resulting in the astaxanthin yield of 51.06 and 40.25 mg L^− 1 which are equivalent to 2.79 and 2.50% of their dry biomass respectively. Based on the laboratory work, 6 batch cultures of H. pluvialis WZ were conducted successfully to produce astaxanthin in two 100 m² open race-way pond by two-stage growth one-step process. The astaxanthin content ranged from 1.61 to 2.48 g 100 g^− 1dry wt., with average astaxanthin content of 2.10 g 100 g^− 1dry wt. Compared with the one-stage production of astaxanthin based on continuous culture, the superiority of our process is that it can accumulate much more astaxanthin in red cysts. Compared with two-stage production of astaxanthin, the advantage of our process is that it does not need to divide the production process into two parts using two bioreactors. The presented work demonstrates the feasibility for producing astaxanthin from Haematococcus using a two-stage growth one-step process in open pond, culture systems that have been successfully used for Spirulina and Chlorella mass culture. The future of Haematococcus astaxanthin production has been also discussed.     

Influence of pond fertilization and feeding rate on growth performance, economic returns and water quality in a small-scale cage-cum-pond integrated system for production of Nile tilapia (Oreochromis niloticus L.)

The effects of pond fertilization and feeding rate on growth, economic returns and water quality were investigated to develop a low‐cost cage‐cum‐pond integrated system for production of Oreochromis niloticus (L.). Hand‐sexed male fingerlings averaging 19±0.39 and 32±0.69 g were stocked in cages and open ponds at 150 fish cage^?1 and 2 fish m^?2 respectively. Fish were cultured for 114 days in five triplicate treatments. Cages were installed into ponds and caged fish were fed a 24% protein diet at 3% (T1) and 6% (T2) body weight day^?1 (BWD) without pond fertilization, and 6% BWD with pond fertilization (T3). The open water in the fourth treatment (T4) was not stocked but contained caged fish, which were fed 6% BWD for the first 57 days followed by 3% BWD for the remaining period. Ponds in the control (T5) had no cages and were neither fertilized nor open‐pond fish fed. Feeding rate and pond fertilization significantly (P<0.05) affected fish growth, profitability and water quality among treatments. Fish growth, feed utilization, fish yield, water quality and profits were significantly (P<0.05) better in T3 than the other treatments. It was concluded that fish production and economic returns were optimized at 6% BWD in fertilized ponds.     

Study on regional production and economy of cobia <Emphasis Type="Italic">Rachycentron canadum</Emphasis> commercial cage culture

In recent years, cobia has become an emerging farmed species in Asia due to its quick growth and high economic value. This study collects biological and economic data affecting the economic performance of cobia farming in three countries, namely Taiwan, China, and Vietnam. The data are collected by questionnaire sampling and analyzed by multivariate statistical analysis in order to compare the key factors affecting the production and economy of cobia farming in these three countries. The results show that Taiwan, China, and Vietnam have significant differences in input intensities and profitability. China has the highest input intensity (3372.42 TWD/m³), as its high stocking density increases feed input. Taiwan has the highest unit input cost (103.44 TWD/kg), as the high quality of the product increases the price of cobia in Taiwan, which offsets the high product costs. In terms of profitability, the benefit–cost ratio is over one in all three countries, indicating that the profitability of cobia farming is good in all three countries. Profitability analysis shows that fingerlings in China achieve 36.50, which is the highest among the three countries; whereas Taiwan has the highest feed profitability of 0.78, which reveals that the fingerlings produced in China are competitive in both price and quality, while Taiwan has the best feed management efficiency. The production costs and profitability of Vietnam fall between those of Taiwan and China. Feed cost is the main expenditure in cobia culture; thus, good feed management could effectively reduce production costs and increase business performance. The feed quality and input management model of Taiwan, in conjunction with the fingerling quality and stock model of China, could provide future reference for farming management in such areas as feed input and selection of fingerling.     

A 13C/12C Tracer Study of the Utilization of Presented Feed by a Commercially Important Shrimp Penaeus vannamei in a Pond Growout System1

A study of added feed utilization by pond grown shrimp was done using seven feeds with different ¹3C/¹²C ratios, as expressed by δ¹³C. The pond shrimp did not track the δ¹³C value of the feed to the extent that tank grown shrimp did. For the seven pond experiments the δ¹³C data indicate that the added feed supplied between 23 and 47% of the growth carbon. This implies that between 53 and 77% of the growth is due to the grazing on pond biota. It is suggested that this experimental approach can be used to evaluate the relative contribution of presented dried feeds versus natural productivity in ponds as an aid to developing pond management strategies and optimum feeds.     

Preliminary Comparisons of Yield and Profit Achieved from Different Rainbow Trout,Oncorhynchus mykiss,Production Systems in Inland Western Australia

Abstract

Farmers throughout the wheatbelt of Western Australia are interested in farming rainbow trout, Oncorhynchus mykiss, in saline groundwater on salt-affected farmland, to generate an alternative source of income. We compared the relative productivity and profitability of three different production systems: extensive (trout stocked in earthen ponds and totally reliant on natural food); semi-intensive (trout stocked in earthen ponds and provided with supplementary diet); intensive (trout stocked in closed, recirculating tanks). The yield of fish increased with increasing production intensity. The mean wet weight (±SE) of trout after 4 months of grow-out was 61.3±2.7 g in extensive systems, 157.9±5.2 g in semi-intensive systems and 137.9±3.9 g in intensive systems, giving mean yields of 10.8 kg/pond (13.5 kg/ha), 27.9 kg/pond (34.8 kg/ha) and 54.9 kg/tank (21.1 kg/m³), respectively. A preliminary economic analysis of the different production systems showed that the increases in yield were sufficient to balance the extra operating costs involved in semi-intensive systems, but not in intensive systems. We conclude that semi-intensive production systems deserve further study for the commercially viable production of rainbow trout from saline groundwater in Western Australia.     

Economic Analysis of Nile Tilapia (Oreochromis niloticus) Production in Tanzania

In Tanzania, Nile tilapia culture is a promising aquaculture enterprise. Information on production costs could assist fish farmers in economic and financial planning. Economic profitability of small‐scale Nile tilapia production in Tanzania is analyzed using a model that simulates individual fish growth and takes into account fish population dynamics in the pond. The results suggest that the current practiced mixed‐sex tilapia culture without predation is not economically sustainable. Extension efforts should be geared toward developing a Nile tilapia production system that is based on a hand‐sexed all‐male tilapia. Meanwhile catfish can be introduced in ponds to control overcrowding in mixed‐sex tilapia culture without predation. Studies to determine optimal pond sizes, availability of feed, and a quality fingerling supply chain are also fundamental for developing a sustainable Nile tilapia production system in Tanzania. Under improved Nile tilapia production systems, returns are high enough to justify investment through borrowed capital from formal institutions.